IMPACT OF SELECTED DRYING METHODS ON THE NUTRITIONAL COMPOSITION OF COMMONLY CONSUMED FISHES IN NIGERIA

Abstract

Food processing, including drying, affects the quality of food product. Among the numerous methods used for food preservation, drying is unquestionably the most ancient but still very much used till date. This research is focused on determining the impact of selected drying methods (sun-drying, smoke-drying and freeze-drying) on the nutritional and chemical composition of some of the commonly consumed fishes in Nigeria (catfish, mackerel, and herring). The proximate, mineral, amino acid, vitamin and fatty acid composition were analyzed using standard methods. Proximate analysis of the samples revealed that smoke-dried herring had the least moisture content (3.34%), highest level of ash (6.72 g/100g DW) and crude protein (38.19 g/100g DW), with a reasonable amount of carbohydrate. Freeze-dried catfish had significantly the highest value of both dietary major and minor minerals. The results of the amino acids analysis revealed that smoke-dried herring had the most abundant essential and non-essential amino acid contents. Meanwhile, the vitamin analysis of the nine fish samples showed vitamin A as the most abundant in the fish samples, with freeze-dried mackerel having the highest significant value for all the six vitamins analyzed. The fatty acid composition of the extracted oil revealed that saturated fatty acid was more abundant compared to mono-unsaturated fatty acid and poly-unsaturated fatty acid. It was therefore concluded that the nutritional and chemical composition of the fish samples were influenced by the selected drying methods while the introduction of freeze-drying technique helped to manage nutritional loss. Overall, the research revealed that fish traders in rural areas with no or irregular power supply can venture in smoke-dried herring business to optimize profit while polycyclic aromatic hydrocarbons analysis of all smoke-dried fish is encouraged.